Fire-resistant roof system and membrane composite

ABSTRACT

A roof assembly comprising: a roof deck; a thermoplastic membrane covering the deck; and a fabric having disposed thereon expandable graphite.

This application is a continuation application of U.S. Non-Provisionalapplication Ser. No. 16/665,765 filed on Oct. 28, 2019, which is acontinuation application of U.S. Non-Provisional application Ser. No.15/354,009 filed on Nov. 17, 2016, which is a continuation applicationof U.S. Non-Provisional application Ser. No. 14/162,273 filed on Jan.23, 2014 and has issued as U.S. Pat. No. 9,523,203, which claims thebenefit of U.S. Provisional Application Ser. No. 61/856,258 filed onJul. 19, 2013, and which also claims the benefit of U.S. Non-Provisionalapplication Ser. No. 13/798,413 filed on Mar. 13, 2013, and claims thebenefit of U.S. Provisional Application Ser. No. 61/755,666 filed onJan. 23, 2013, which are incorporated herein by reference.

FIELD OF THE INVENTION

Embodiments of the present invention are directed toward afire-resistant roofing system including a deck and a thermoplasticmembrane composite.

BACKGROUND OF THE INVENTION

As is known in the art, roofs can be rated according to UL 790 or ASTM E108 standards for fire resistance. A Class A roof has the highestresistance to fire. An unrated roof has the lowest resistance to fire,and class B and class C rated roofs are rated therebetween,respectively. These ratings are generally based upon flame penetrationinto the attic space through the roof covering, flame spread over thesurface of the roof covering, and the propensity for the roof coveringto become dislodged and generate embers.

Certain non-combustible roof decks can achieve a Class A rating byvirtue of their construction. For example, a concrete deck typicallyachieves a Class A rating. Other roofs, such as those carrying analuminum covering, may require complementary materials to achieve aClass A rating. For example, an asphaltic underlayment may be placedunder an aluminum roof covering to achieve a Class A rating.

Where the roof deck is a combustible deck, such as a wood deck, it canbe extremely difficult to achieve a Class A rating. In many situations,robust and expensive underlayment is required to achieve a Class Arating over a combustible deck. For example, fiberglass-backed gypsumboard (e.g., DensDeck™) can be applied over a combustible deck toachieve a Class A rating. Alternatively, or in addition thereto, a heavyunderlayment (e.g., 72 pound felt or cap sheet) may be required toachieve a Class A rating over a wood roof deck.

The difficulty in achieving a Class A rating can be further complicatedby the type of roof covering employed over the combustible deck. Where aroof covering is metal (e.g., aluminum), the complementary constructionmaterial, such as an underlayment, may not need to be as robust toachieve a Class A rating. On the other hand, where the roof covering isa polymeric membrane (e.g., a thermoplastic sheet), the ability toachieve a Class A rating over a combustible deck is not trivial.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a roof system according toembodiments of the invention.

FIG. 2 is a perspective, exploded view of a thermoplastic membranehaving a fabric reinforcement according to embodiments of the presentinvention.

FIG. 3 is a cross-sectional view of a thermoplastic membrane having afabric backing according to embodiments of the invention.

FIG. 4 is a cross-sectional view of a thermoplastic membrane including alap edge according to embodiments of the invention.

SUMMARY OF THE INVENTION

Aspects of the invention provide a roof assembly comprising: a roofdeck; a thermoplastic membrane covering the deck; and a fabric havingdisposed thereon expandable graphite.

Other aspects provide a membrane composite comprising: a thermoplasticmembrane; and a fabric carrying expandable graphite.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Embodiments of the present invention are based, at least in part, on thediscovery of a fire-rated roof system (e.g., Class A roof system (UL 790or ASTM E 108) using a thermoplastic membrane over a wood deck at aslope of 1/12) that includes a polymeric membrane composite. Thecomposite includes a polymeric membrane in combination with a fabricthat carries expandable graphite. In one or more embodiments, thecomposite includes a thermoplastic membrane and a fabric reinforcementthat carries expandable graphite. In other embodiments, the compositeincludes a thermoplastic membrane and a fabric backing that carriesexpandable graphite. While the prior art could achieve a similar Class Arating using relatively robust and expensive complementary materials(e.g. fiberglass-backed gypsum), the present invention advantageouslyachieves a Class A rating by merely employing the composite of theinvention without any other fire-barrier material (e.g. without a fireresistant slipsheet or fiberglass-backed board). Moreover, theseadvantages are provided in conjunction with weathering protection (i.e.waterproof membrane) in one single composite article. Among otherbenefits, the use of the composite of the present invention simplifiesinstallation and saves in labor costs associated with installation. ROOFSYSTEM

In one or more embodiments, the Class A roof system of the presentinvention may be described with reference to FIG. 1. System 10 includesa combustible deck 12, an optional insulating layer 14, and one or morethermoplastic membrane composites 16 and 16′, which may also be referredto as sheets 16 and 16′ or panels 16 and 16′. Each of the respectivepanels may be referred to as membrane assemblies, especially whendescribing the subcomponents thereof. As indicated above, and as will bedescribed in greater detail below, membrane assemblies 16 and 16′include a fabric that carries expandable graphite. Membrane assemblies16 and 16′ may be secured to deck 12 and/or insulating layer 14 by usingknown techniques. In one or more embodiments, membrane assemblies 16 and16′ are mechanically attached to deck 12 through a plurality ofmechanical fasteners. For example, fastener 18 may be installed in lapregion 17 of membrane assemblies 16 and 16′ as shown in FIG. 1.

In other embodiments, membrane assembly 16 may be secured to deck 12and/or insulation layer 14 by use of an adhesive that may, in certainembodiments, secure substantially all of the membrane to deck 12 and/orinsulating layer 14, and thereby provide a system that may be referredto as a fully-adhered roofing system. The use of an adhesive to securethe membrane panels to the roof deck and/or insulation layer may be anexclusive mode of attachment to the roof deck and/or insulation layer,or an adhesive may be used in combination with other modes ofattachment. In one or more embodiments, the use of an adhesive forms anadhesive layer 20. As will be described in further detail below,adhesive layer 20 may be interspersed within and/or adhered to a fabricbacking, which is not shown in FIG. 1. In yet other embodiments,membrane 16 may be secured to deck 12 and/or insulation layer 14 by useof ballasting as is known in the art.

As the skilled person understands, panels 16 and 16′ are not onlysecured to deck 12 and/or insulation layer 14, but the individual panelsmay be seamed together to create a water-impervious membrane across theroof deck. As shown in FIG. 1, individual panels 16 and 16′ are seamedtogether in lap region 17, where first panel 16′ overlaps second panel16. As previously explained, fasteners (e.g. fastener 18) may bedisposed in lap region 17, thereby allowing second panel 16 to coverfastener 18, as well as any penetrations caused by fastener 18. Theskilled person will appreciate that lap region 17 may be seamed using avariety of techniques. In one or more embodiments, the seam may beformed by heat welding the respective panels to each other within lapregion 17. This may be accomplished by taking advantage of thethermoplastic nature of the panels. Techniques for heat weldingthermoplastic membranes are known in the art as described in U.S.Publication Nos 2007/0186505, 2004/0020585, 2002/0003026, 2011/0155321,2007/0208139, and 2005/0183831, which are incorporated herein byreference. In other embodiments, a seam tape or liquid adhesive may beemployed to form a seam within lap region 17.

Membrane Assembly

In one or more embodiments, thermoplastic membrane assembly 16 includesreinforcing fabric 24 as shown in FIG. 2. More specifically, membrane 16is a laminate including first layer 26, second layer 28, and reinforcingfabric 24 laminated between first layer 26 and second layer 28.

Thermoplastic Layers

Embodiments of the present invention are not necessarily limited by thecomposition of the individual thermoplastic layers of the thermoplasticmembrane (e.g. layers 26 and 28). In one or more embodiments, thethermoplastic layers may include thermoplastic polyolefins, polyvinylchloride, ethylene vinylacetate polymers, ethylene alkylacrylatepolymers, and the like, and mixtures thereof.

In one or more embodiments, the thermoplastic polyolefin polymers mayinclude an olefinic reactor copolymer, which may also be referred to asin-reactor copolymer. Reactor copolymers are generally known in the artand may include blends of olefinic polymers that result from thepolymerization of ethylene and α-olefins (e.g. propylene) with sundrycatalyst systems. In one or more embodiments, these blends are made byin-reactor sequential polymerization. Reactor copolymers useful in oneor more embodiments include those disclosed in U.S. Pat. No. 6,451,897,which is incorporated therein by reference. Reactor copolymers, whichare also referred to as TPO resins, are commercially available under thetradename HIFAX™ (Lyondellbassel); these materials are believed toinclude in-reactor blends of ethylene-propylene rubber and polypropyleneor polypropylene copolymers. In one or more embodiments, the in-reactorcopolymers may be physically blended with other polyolefins. Forexample, in reactor copolymers may be blended with linear low densitypolyethene.

In other embodiments, the thermoplastic polyolefin polymers may includeone or more polyolefins such as, but not limited to, propylene-basedthermoplastic polymers, plastomers, and/or ethylene-based thermoplasticpolymers. In one or more embodiments, the thermoplastic polymer mayinclude a blend of olefinic polymers. Useful blends include thosedescribed in International Application No. PCT/US06/033522 which isincorporated herein by reference. For example, a particular blend mayinclude (i) a plastomer, (ii) a low density polyethylene, and (iii) apropylene-based polymer.

In one or more embodiments, propylene-based polymers may includepolypropylene homopolymer or copolymers of propylene and a comonomer,where the copolymer includes, on a mole basis, a majority of mer unitsderiving from propylene. In one or more embodiments, the propylene-basedcopolymers may include from about 2 to about 6 mole percent, and inother embodiments from about 3 to about 5 mole percent mer unitsderiving from the comonomer with the remainder including mer unitsderiving from propylene. In one or more embodiments, the comonomerincludes at least one of ethylene and an α-olefin. The α-olefins mayinclude butene-1, pentene-1, hexene-1, octene-1, or 4-methyl-pentene-1.In one or more embodiments, the copolymers of propylene and a comonomermay include random copolymers. Random copolymers may include thosepropylene-based copolymers where the comonomer is randomly distributedacross the polymer backbone.

The propylene-based polymers employed in one or more embodiments of thisinvention may be characterized by a melt flow rate of from about 0.5 toabout 15 dg/min, in other embodiments from about 0.7 to about 12 dg/min,in other embodiments from about 1 to about 10 dg/min, and in otherembodiments from about 1.5 to about 3 dg/min per ASTM D-1238 at 230° C.and 2.16 kg load. In these or other embodiments, the propylene-basedpolymers may have a weight average molecular weight (M_(w)) of fromabout 1×10⁵ to about 5×10⁵ g/mole, in other embodiments from about 2×10⁵to about 4×10⁵ g/mole, and in other embodiments from about 3×10⁵ toabout 4×10⁵ g/mole, as measured by GPC with polystyrene standards. Themolecular weight distribution of these propylene-based copolymer may befrom about 2.5 to about 4, in other embodiments from about 2.7 to about3.5, and in other embodiments from about 2.8 to about 3.2.

In one or more embodiments, propylene-based polymers may becharacterized by a melt temperature (T_(m)) that is from about 165° C.to about 130° C., in other embodiments from about 160 to about 140° C.,and in other embodiments from about 155° C. to about 140° C. In one ormore embodiments, particularly where the propylene-based polymer is acopolymer of propylene and a comonomer, the melt temperature may bebelow 160° C., in other embodiments below 155° C., in other embodimentsbelow 150° C., and in other embodiments below 145° C. In one or moreembodiments, they may have a crystallization temperature (T_(c)) ofabout at least 90° C., in other embodiments at least about 95° C., andin other embodiments at least 100° C., with one embodiment ranging from105° to 115° C.

Also, these propylene-based polymers may be characterized by having aheat of fusion of at least 25 J/g, in other embodiments in excess of 50J/g, in other embodiments in excess of 100 J/g, and in other embodimentsin excess of 140 J/g.

In one or more embodiments, the propylene-based polymers may becharacterized by a flexural modulus, which may also be referred to as a1% secant modulus, in excess of 120,000 psi, in other embodiments inexcess of 125,000, in other embodiments in excess of 130,000 psi, inother embodiments in excess of 133,000 psi, in other embodiments inexcess of 135,000 psi, and in other embodiments in excess of 137,000psi, as measured according to ASTM D-790.

Useful propylene-based polymers include those that are commerciallyavailable. For example, propylene-based polymers can be obtained underthe tradename PP7620Z™ (Fina), PP33BF01™ (Equistar), or under thetradename TR3020™ (Sunoco).

In one or more embodiments, plastomers include ethylene-α-olefincopolymers. The plastomer employed in one or more embodiments of thisinvention includes those described in U.S. Pat. Nos. 6,207,754,6,506,842, 5,226,392, and 5,747,592, which are incorporated herein byreference. This copolymer may include from about 1.0 to about 15 molepercent, in other embodiments from about 2 to about 12, in otherembodiments from about 3 to about 9 mole percent, and in otherembodiments from about 3.5 to about 8 mole percent mer units derivingfrom α-olefins, with the balance including mer units deriving fromethylene. The α-olefin employed in preparing the plastomer of one ormore embodiments of this invention may include butene-1, pentene-1,hexene-1, octene-1, or 4-methyl-pentene-1.

In one or more embodiments, plastomers may be characterized by a densityof from about 0.865 g/cc to about 0.900 g/cc, in other embodiments fromabout 0.870 to about 0.890 g/cc, and in other embodiments from about0.875 to about 0.880 g/cc per ASTM D-792. In these or other embodiments,the density of the plastomers may be less than 0.900 g/cc, in otherembodiments less than 0.890 g/cc, in other embodiments less than 0.880g/cc, and in other embodiments less than 0.875 g/cc.

In one or more embodiments, the plastomer may be characterized by aweight average molecular weight of from about 7×10⁴ to 13×10⁴ g/mole, inother embodiments from about 8×10⁴ to about 12×10⁴ g/mole, and in otherembodiments from about 9×10⁴ to about 11×10⁴ g/mole as measured by usingGPC with polystyrene standards. In these or other embodiments, theplastomer may be characterized by a weight average molecular weight inexcess of 5×10⁴ g/mole, in other embodiments in excess of 6×10⁴ g/mole,in other embodiments in excess of 7×10⁴ g/mole, and in other embodimentsin excess of 9×10⁴ g/mole. In these or other embodiments, the plastomermay be characterized by a molecular weight distribution (M_(w)/M_(n))that is from about 1.5 to 2.8, in other embodiments 1.7 to 2.4, and inother embodiments 2 to 2.3.

In these or other embodiments, the plastomer may be characterized by amelt index of from about 0.1 to about 8, in other embodiments from about0.3 to about 7, and in other embodiments from about 0.5 to about 5 perASTM D-1238 at 190° C. and 2.16 kg load.

The uniformity of the comonomer distribution of the plastomer of one ormore embodiments, when expressed as a comonomer distribution breadthindex value (CDBI), provides for a CDBI of greater than 60, in otherembodiments greater than 80, and in other embodiments greater than 90.

In one or more embodiments, the plastomer may be characterized by a DSCmelting point curve that exhibits the occurrence of a single meltingpoint break occurring in the region of 50 to 110° C.

The plastomer of one or more embodiments of this invention may beprepared by using a single-site coordination catalyst includingmetallocene catalyst, which are conventionally known in the art.

Useful plastomers include those that are commercially available. Forexample, plastomer can be obtained under the tradename EXXACT™ 8201(ExxonMobil); or under the tradename ENGAGE™ 8180 (Dow DuPont). In oneor more embodiments, the low density polyethylene includes anethylene-α-olefin copolymer. In one or more embodiments, the low densitypolyethylene includes linear low density polyethylene. The linear lowdensity polyethylene employed in one or more embodiments of thisinvention may be similar to that described in U.S. Pat. No. 5,266,392,which is incorporated herein by reference. This copolymer may includefrom about 2.5 to about 13 mole percent, and in other embodiments fromabout 3.5 to about 10 mole percent, mer units deriving from α-olefins,with the balance including mer units deriving from ethylene. Theα-olefin included in the linear low density polyethylene of one or moreembodiments of this invention may include butene-1, pentene-1, hexene-1,octene-1, or 4-methyl-pentene-1. In one or more embodiments, the linearlow density polyethylene is devoid or substantially devoid of propylenemer units (i.e., units deriving from propylene). Substantially devoidrefers to that amount or less of propylene mer units that wouldotherwise have an appreciable impact on the copolymer or thecompositions of this invention if present.

The linear low density polyethylene of one or more embodiments of thisinvention can be characterized by a density of from about 0.885 g/cc toabout 0.930 g/cc, in other embodiments from about 0.900 g/cc to about0.920 g/cc, and in other embodiments from about 0.900 g/cc to about0.910 g/cc per ASTM D-792.

In one or more embodiments, the linear low density polyethylene may becharacterized by a weight average molecular weight of from about 1×10⁵to about 5×10⁵ g/mole, in other embodiments 2×10⁵ to about 10×10⁵g/mole, in other embodiments from about 5×10⁵ to about 8×10⁵ g/mole, andin other embodiments from about 6×10⁵ to about 7×10⁵ g/mole as measuredby GPC with polystyrene standards. In these or other embodiments, thelinear low density polyethylene may be characterized by a molecularweight distribution (M_(w)/M_(n)) of from about 2.5 to about 25, inother embodiments from about 3 to about 20, and in other embodimentsfrom about 3.5 to about 10. In these or other embodiments, the linearlow density polyethylene may be characterized by a melt flow rate offrom about 0.2 to about 10 dg/min, in other embodiments from about 0.4to about 5 dg/min, and in other embodiments from about 0.6 to about 2dg/min per ASTM D-1238 at 230° C. and 2.16 kg load.

The linear low density polyethylene of one or more embodiments of thisinvention may be prepared by using a convention Ziegler Nattacoordination catalyst system.

Useful linear low density polyethylene includes those that arecommercially available. For example, linear low density polyethylene canbe obtained under the tradename Dowlex™ 2267G (Dow); or under thetradename DFDA-1010 NT7 (Dow); or under the tradename GA502023(Lyondell).

In one or more embodiments, useful thermoplastic vulcanizates includethose available under the tradename UniPrene (Teknor Apex)® andSantoprene (ExxonMobil)®.

Useful ethylene alkyl-acrylates include those available under thetradename ELVALOY® (DuPont).

In one or more embodiments, block copolymers that may be used includestyrene-butadiene block copolymers such as, but not limited to,styrene-butadiene-styrene block copolymers. These block copolymers maybe blended with polyolefins such as polypropylene to form thermoplasticcompositions that are useful in the practice of this invention.

In one or more embodiments, thermoplastic polyolefins may includepropylene-based elastomers such as those available under the tradenamesVISTAMAXX (ExxonMobil) and VERSIFY (Dow Chemical).

In one or more embodiments, the thermoplastic polymer or polymersforming the thermoplastic matrix in which the expandable graphite isdispersed has a melt temperature below 200° C., in other embodimentsbelow 180° C., in other embodiments below 160° C., and in otherembodiments below 150° C.

In one or more embodiments, layers 26 and 28 may be characterized by athickness of from about 15 to about 70, in other embodiments from about20 to about 60 mils, and in other embodiments from about 30 to about 50.

In one or more embodiments, layers 26 and/or 28 may be homogenous; i.e.,they may be monoextruded sheets or layers of thermoplastic material. Inother embodiments, layers 26 and 28 may include two or more co-extrudedlayers. These individual co-extruded layers of any given layer of thelaminate (e.g., layer 26 and/or 28) may be distinct from othercoextruded layers within any respective laminate layer. Multi-layered,co-extruded thermoplastic roofing membranes are known in the art asdescribed in U.S. Pat. Nos. 7,749,924, 7,632,763, 5,314,556, and U.S.Publication Nos 2012/0244340, 2009/0181216, 2009/0137168, 2007/0194482,and 2007/0193167, which are incorporated herein by reference.

Reinforcing Fabric/Scrim

As discussed above, membranes 16 and 16′ may include reinforcing fabric24. In one or more embodiments, reinforcing fabric 24 includes a fabricsubstrate having disposed on a surface thereof particles of expandablegraphite. For example, as shown in FIG. 2, fabric 24 includes fabricsubstrate 30 and expandable graphite 32 disposed on a surface ofsubstrate 30. In one or more embodiments, expandable graphite 32 may bedispersed within a polymeric matrix 34, which may also be referred to asbinder 34, that is disposed on fabric substrate 30. In this regard,reference may be made to an expandable graphite coating 31 disposed onfabric substrate 30. As shown in FIG. 2, coating 31 may form a layer orpartial layer on the fibers or filaments of substrate 30. In otherembodiments, coating 31 forms a layer or partial layer over the entiresurface of substrate 30.

In one or more embodiments, fabric substrate 24 may include a woven,knitted, or non-woven fabric. In particular embodiments, fabricsubstrate 24 may be of the type of fabric generally known in the art forpreparing roofing membranes. Useful fabric substrates include warp-knit,weft-inserted fabrics, such as those that as are known in the art and,for example, described in U.S. Pat. Nos. 4,491,617, 4,539,254,4,615,934, and 4,780,350, which are incorporated herein by reference.

Expandable Graphite

In one or more embodiments, expandable graphite, which may also bereferred to as expandable flake graphite, intumescent flake graphite, orexpandable flake, includes intercalated graphite in which anintercallant material is included between the graphite layers ofgraphite crystal or particle. Examples of intercallant materials includehalogens, alkali metals, sulfates, nitrates, various organic acids,aluminum chlorides, ferric chlorides, other metal halides, arsenicsulfides, and thallium sulfides. In certain embodiments of the presentinvention, the expandable graphite includes non-halogenated intercallantmaterials. In certain embodiments, the expandable graphite includessulfate intercallants, also referred to as graphite bisulfate. As isknown in the art, bisulfate intercalation is achieved by treating highlycrystalline natural flake graphite with a mixture of sulfuric acid andother oxidizing agents which act to catalyze the sulfate intercalation.

Commercially available examples of expandable graphite include HPMSExpandable Graphite (HP Materials Solutions, Inc., Woodland Hills,Calif.) and Expandable Graphite Grades 1721 (Asbury Carbons, Asbury,N.J.). Other commercial grades contemplated as useful in the presentinvention include 1722, 3393, 3577, 3626, and 1722HT (Asbury Carbons,Asbury, N.J.).

In one or more embodiments, the expandable graphite may be characterizedas having a mean or average size in the range from about 30 μm to about1.5 mm, in other embodiments from about 50 μm to about 1.0 mm, and inother embodiments from about 180 to about 850 μm. In certainembodiments, the expandable graphite may be characterized as having amean or average size of at least 30 μm, in other embodiments at least 44μm, in other embodiments at least 180 μm, and in other embodiments atleast 300 μm. In one or more embodiments, expandable graphite may becharacterized as having a mean or average size of at most 1.5 mm, inother embodiments at most 1.0 mm, in other embodiments at most 850 μm,in other embodiments at most 600 μm, in yet other embodiments at most500 μm, and in still other embodiments at most 400 μm. Useful expandablegraphite includes Graphite Grade #1721 (Asbury Carbons), which has anominal size of greater than 300 μm.

In one or more embodiments of the present invention, the expandablegraphite may be characterized as having a nominal particle size of 20×50(US sieve). US sieve 20 has an opening equivalent to 0.841 mm and USsieve 50 has an opening equivalent to 0.297 mm. Therefore, a nominalparticle size of 20×50 indicates the graphite particles are at least0.297 mm and at most 0.841 mm.

In one or more embodiments, the expandable graphite may be characterizedas having a carbon content in the range from about 75% to about 99%. Incertain embodiments, the expandable graphite may be characterized ashaving a carbon content of at least 80%, in other embodiments at least85%, in other embodiments at least 90%, in yet other embodiments atleast 95%, in other embodiments at least 98%, and in still otherembodiments at least 99% carbon.

In one or more embodiments, the expandable graphite may be characterizedas having a sulfur content in the range from about 0% to about 8%, inother embodiments from about 2.6% to about 5.0%, and in otherembodiments from about 3.0% to about 3.5%. In certain embodiments, theexpandable graphite may be characterized as having a sulfur content ofat least 0%, in other embodiments at least 2.6%, in other embodiments atleast 2.9%, in other embodiments at least 3.2%, and in other embodiments3.5%. In certain embodiments, the expandable graphite may becharacterized as having a sulfur content of at most 8%, in otherembodiments at most 5%, in other embodiments at most 3.5%.

In one or more embodiments, the expandable graphite may be characterizedas having an expansion ratio (cc/g) in the range from about 10:1 toabout 500:1, in other embodiments at least 20:1 to about 450:1, in otherembodiments at least 30:1 to about 400:1, in other embodiments fromabout 50:1 to about 350:1. In certain embodiments, the expandablegraphite may be characterized as having an expansion ratio (cc/g) of atleast 10:1, in other embodiments at least 20:1, in other embodiments atleast 30:1, in other embodiments at least 40:1, in other embodiments atleast 50:1, in other embodiments at least 60:1, in other embodiments atleast 90:1, in other embodiments at least 160:1, in other embodiments atleast 210:1, in other embodiments at least 220:1, in other embodimentsat least 230:1, in other embodiments at least 270:1, in otherembodiments at least 290:1, and in yet other embodiments at least 300:1.In certain embodiments, the expandable graphite may be characterized ashaving an expansion ratio (cc/g) of at most 350:1, and in yet otherembodiments at most 300:1.

In one or more embodiments, the expandable graphite, as it exists withthe thermoplastic component of the thermoplastic membrane of the presentinvention, may be partially expanded. In one or more embodiments, theexpandable graphite is not expanded, however, to a deleterious degree,which includes that amount or more of expansion that will deleteriouslyimpact the ability to form the sheet product and/or the ability of thegraphite to serve as flame retardant at desirable levels, which includethose levels that allow proper formation of the sheet. In one or moreembodiments, the expandable graphite is expanded to at most 60%, inother embodiments at most 50%, in other embodiments at most 40%, inother embodiments at most 30%, in other embodiments at most 20%, and inother embodiments at most 10% beyond its original unexpanded size.

In one or more embodiments, the expandable graphite may be characterizedas having a pH in the range from about 1 to about 12; in otherembodiments from about 1 to about 6; and in yet other embodiments fromabout 5 to about 10. In certain embodiments, the expandable graphite maybe characterized as having a pH in the range from about 4 to about 7. Inone or more embodiments, the expandable graphite may be characterized ashaving a pH of at least 1, in other embodiments at least 4, and in otherembodiments at least 5. In certain embodiments, the expandable graphitemay be characterized as having a pH of at most 10, in other embodimentsat most 7, and in other embodiments at most 6.

In one or more embodiments, the expandable graphite may be characterizedby an onset temperature ranging from about 100° C. to about 250° C.; inother embodiments from about 160° C. to about 225° C.; and in otherembodiments from about 180° C. to about 200° C. In one or moreembodiments, the expandable graphite may be characterized by an onsettemperature of at least 100° C., in other embodiments at least 130° C.,in other embodiments at least 160° C., and in other embodiments at least180° C. In one or more embodiments, the expandable graphite may becharacterized by an onset temperature of at most 250° C., in otherembodiments at most 225° C., and in other embodiments at most 200° C.Onset temperature may also be interchangeably referred to as expansiontemperature; and may also be referred to as the temperature at whichexpansion of the graphite starts.

Complementary Flame Retardants

In one or more embodiments, the expandable graphite may be disposed onthe fabric substrate in conjunction with a complementary flameretardant. These complementary flame retardants may include any compoundthat increases the burn resistivity, particularly flame spread such astested by UL 94 and/or UL 790, in the polymeric compositions of thepresent invention. Generally, useful flame retardants include those thatoperate by forming a char-layer across the surface of a specimen whenexposed to a flame. Other flame retardants include those that operate byreleasing water upon thermal decomposition of the flame retardantcompound. Useful flame retardants may also be categorized as halogenatedflame retardants or non-halogenated flame retardants.

Exemplary non-halogenated flame retardants include magnesium hydroxide,aluminum trihydrate, zinc borate, ammonium polyphosphate, melaminepolyphosphate, and antimony oxide (Sb₂O₃). Magnesium hydroxide (Mg(OH)₂)is commercially available under the tradename Vertex™ 60, ammoniumpolyphosphate is commercially available under the tradename Exolite™ AP760 (Clarian), melamine polyphosphate is available under the tradenameBudit™ 3141 (Budenheim), and antimony oxide (Sb₂O₃) is commerciallyavailable under the tradename Fireshield™.

Examples of other complementary calcium borate, magnesium hydroxide,basic magnesium carbonate, aluminum trihydrate, zinc borate, gypsum, andmixtures thereof. In these or other embodiments, the complementary flameretardant includes colemanite, which is a borate mineral that isbelieved to include about 50-80% calcium borate.

Coating

As noted above, fabric reinforcement 24 may carry (i.e. have disposedthereon) coating 31 that includes binder 34 with expandable graphite 32dispersed therein. The binder, which may also be referred to as apolymer latex or polymer latex binder, may include, but is not limitedto, styrene-butadiene-rubber (SBR), styrene-butadiene-styrene (SBS),ethylene-vinyl-chloride (EVCl), poly-vinylidene-chloride (PVdC),modified poly-vinyl-chloride (PVC), poly-vinyl-alcohol (PVOH),ethylene-vinyl-actate (EVA), and poly-vinyl-acetate (PVA). In one ormore embodiments, the binder may include an asphalt. In otherembodiments, the binder is devoid of asphalt. In still otherembodiments, the binder may include acrylic or epoxy binders or resins,which are known in the art. Generally, acrylic binders or resins includelatex polymers that derive from the polymerization of acrylates, acrylicacids, methacrylates, methacrylic acids, acrylonitrile, and/oracrylamide monomer. In other embodiments, the binder may include apolyurethane.

Examples of inorganic binders that may be used with the latex bindersinclude, but are not limited to, calcium oxide, calcium silicate,calcium sulfate, magnesium oxychloride, magnesium oxysulfate, and othercomplexes of some Group IIA elements (alkaline earth metals), as well asaluminum hydroxide.

In one or more embodiments, a complex inorganic binder such as portlandcement, which is a mixture of various calcium-aluminum silicates, may beused. In other embodiments, the oxychloride or oxysulfate of aluminumhydroxide and/or calcium silicate may also be used. In yet otherembodiments, quicklime, which does not hydrate in a coating mix, butcures by slowly converting to limestone by adding carbon dioxide fromthe air, may be used, acrylonitrile, and/or acrylamide monomer. In otherembodiments, the binder may include a polyurethane.

In one or embodiments, the coating composition may be characterized bythe weight ratio of polymer to solids within the composition (i.e. inthe cured coating). In one or more embodiments, the weight ratio ofpolymer to solids is at least 0.1:1, in other embodiments at least0.3:1, in other embodiments at least 0.5:1, in other embodiments atleast 0.7:1, and in other embodiments at least 0.7:1. In these or otherembodiments, the weight ratio of polymer to solids is from about 0.1:1to about 3:1, in other embodiments from about 0.3:1 to about 2:1, and inother embodiments from about 0.4:1 to about 0.8:1. It is contemplatedthat at higher polymer loadings, the coating composition will impartless stiffness to the fabric, and thereby advantageously allow thefabric to maintain useful flexibility. This is important, especiallywhere the fabric is used as a backing, because the composite materialsof the invention are desirably rolled for storage and shipment, unrolledduring installation, and manipulated in corners and the like duringinstallation. Thus, maintaining flexibility and/or not inhibiting theflexibility of the membrane and overall composite is technologicallyimportant.

In one or embodiments, the coating composition may be characterized bythe weight of expandable graphite within the composition (i.e. in thecured coating). In one or more embodiments, the weight of expandablegraphite within the coating is at least 2 wt. %, in other embodiments atleast 5 wt. %, in other embodiments at least 8 wt. %, in otherembodiments at least 10 wt. %, and in other embodiments at least 15 wt.%. In these or other embodiments, the weight ratio of polymer to solidsis from about 2 to about 50, in other embodiments from about 5 to about35, and in other embodiments from about 10 to about 25 wt. %.

Fabric Backing

As indicated above, an alternative embodiment of the invention includesa membrane assembly, which may also be referred to as a composite, asshown in FIG. 3 where composite 40 includes fabric backing 42 adhered orotherwise secured to a planar surface 47 of membrane 46. Membrane 46 mayinclude the features of the membranes described above with respect tomembrane 16 (e.g. they may include fabric reinforcement 24 laminatedbetween thermoplastic layer 26 and 28), or thermoplastic membrane 46 mayhave distinct features. Where membrane assembly 40 includes fabricreinforcement 24, fabric reinforcement 24 may carry a coating layer thatincludes expandable graphite, as described above, or it may be devoid orsubstantially devoid of a coating that includes expandable graphite. Inone or more embodiments, membrane 46 is an unreinforced membrane; i.e.membrane 46 is devoid of reinforcement 24. In one or more embodiments,membrane 46 may include a laminated structure that may include one ormore extruded layers laminated to one another. In other embodiments,membrane 46 is a single extrudate. Whether or not membrane 46 includesone or more extrudates, each extrudate may, as described above, includetwo or more coextruded layers of similar or dissimilar thermoplasticcompositions.

In one or more embodiments, fabric backing 42 includes a fabricsubstrate with expandable graphite disposed on a surface thereof. Forexample, as shown in FIG. 3, fabric 42 includes fabric substrate 44 andexpandable graphite 32 disposed on a surface of substrate 44. In one ormore embodiments, expandable graphite 32 may be dispersed within apolymeric matrix 48, which may also be referred to as binder 48,disposed on fabric substrate 44 in the form of a coating 51. As shown inFIG. 3, coating 31 may form a layer or partial layer on the fibers orfilaments of substrate 44. In other embodiments, coating 51 forms alayer or partial layer over the entire surface of substrate 44.Reference can be made to the expandable graphite and binders describedabove for practice of these embodiments.

In one or more embodiments, fabric substrate 44 is a synthetic fabricincluding glass or polymeric fibers or filaments. In particularembodiments, fabric backing 42 is a fleece, such as a napped fleece.Fleece backings of the type that are useful as fabric backings forroofing membranes are generally known in the art as described in U.S.Pat. Nos. 4,996,812, 5,422,179, 5,981,030, and 6,502,360 which areincorporated herein by reference. In particular embodiments, fabricsubstrate 44 is fleece prepared from polyester filaments such as thoseprepared from polyethylene terephthalate. In one or more embodiments,the fabric backing is a continuous filament polyester, needle punched,nonwoven fabric. In other embodiments, the fabric backing is a scrimreinforced nonwoven polyester mat. In yet other embodiments, the fabricbacking is a glass fiber mat.

In one or more embodiments, where the fabric backing is a glass fibermat, the fabric may be characterized by a basis weight of at least 50,in other embodiments at least 60, and in other embodiments at least 70g/m². In these or other embodiments, the glass fiber mat may becharacterized by a basis weight of at most 150, in other embodiments atmost 130, and in other embodiments at most 100 g/m². In one or moreembodiments, the glass fiber mat may be characterized by a basis weightof from about 50 to about 150 g/m², in other embodiments from about 60to about 130 g/m², and in other embodiments from about 70 to about 110g/m².

In one or more embodiments, where the fabric backing is a glass fibermat, the glass mat may be characterized by a thickness of at least 0.5mm, in other embodiments at least 0.7 mm, and in other embodiments atleast 1.0 mm. In these or other embodiments, the glass mat may becharacterized by a thickness of at most 2.0 mm, in other embodiments atmost 1.5 mm, and in other embodiments at most 1.2 mm. In one or moreembodiments, the glass mat may be characterized by a thickness of fromabout 0.5 to about 2.0 mm, in other embodiments from about 0.7 to about1.5 mm, and in other embodiments from about 1.0 to about 1.2 mm.

In one or more embodiments, where the fabric backing is a polyesterfleece, the fabric may be characterized by a basis weight of at least70, in other embodiments at least 85, and in other embodiments at least100 g/m². In these or other embodiments, the polyester fleece may becharacterized by a basis weight of at most 400, in other embodiments atmost 300, and in other embodiments at most 280 g/m². In one or moreembodiments, the polyester fleece may be characterized by a basis weightof from about 70 to about 400 g/m², in other embodiments from about 85to about 300 g/m², and in other embodiments from about 100 to about 280g/m².

In one or more embodiments, where the fabric backing is a polyesterfleece, the glass mat may be characterized by a thickness of at least0.5 mm, in other embodiments at least 0.7 mm, and in other embodimentsat least 1.0 mm. In these or other embodiments, the polyester fleece maybe characterized by a thickness of at most 4.0 mm, in other embodimentsat most 2.0 mm, and in other embodiments at most 1.5 mm. In one or moreembodiments, the polyester fleece may be characterized by a thickness offrom about 0.5 to about 4.0 mm, in other embodiments from about 0.7 toabout 2.0 mm, and in other embodiments from about 1.0 to about 1.5 mm.

Practice of one or more embodiments of the invention is not limited bythe manner in which fabric backing 42 is attached to membrane 46. In oneor more embodiments, fabric backing 42 is secured to membrane 46 by heatlamination; in other words, the membrane and fabric backing are matedwhile the membrane has a degree of tack resulting from heating themembrane (e.g. thermoplastic). In other embodiments, fabric backing 42is secured to membrane 46 by way of an adhesive; for example asolvent-based or hot melt hydrocarbon polymer such as SBS or SBR may beused. In yet other embodiments, fabric backing 42 is secured to membrane46 through the use of a tie layer, which may include a thin film ofadhesive material or hot melt material. In one or more embodiments, themode of attachment is sufficient to create a bond between fabric backing42 and membrane 46 such that during handling, installation and use thefabric backing maintains adherence to the membrane under conventionalconditions.

In one or more embodiments, the coating composition (i.e. the expandablegraphite and the binder) is applied (i.e. disposed on) to one surface ofthe backing opposite the surface that the backing is secured to themembrane. This can be achieved through an application method whereby thecoating composition is applied to only one planar surface of the fabric.As a result, the amount of coating material that exists on a first sideof the fabric is substantially greater than the amount of coating thatexists on the opposite second side of the fabric. It is contemplatedthat this configuration will allow for maximum adhesion of the fabric tothe surface of the membrane to which it is attached.

In one or more embodiments, where the composite includes a fabricbacking, the fabric backing is attached to only a portion of themembrane surface. In particular embodiments, a lap edge is maintained inthe membrane for seaming adjacent membranes together. This seaming cantake place through heat seaming or adhesive seaming. An example of acomposite membrane including a lap seam is shown in FIG. 4, wherecomposite 60 includes membrane 62, and fabric backing 64, which isconsistent with embodiments of the invention and carries expandablegraphite. Composite 60 includes lap edge 66, which extends laterallyalong the length of the membrane down an edge thereof. Lap edge 66allows for membrane 62 to be exposed and thereby allows for seaming ofadjacent membranes. In general, lap edge 66 could be 2-12″ inches inwidth, although the width can vary depending on preference.

In one or more embodiments, the fabric backing may be characterized bythe concentration of expandable graphite contained therein, which asdescried herein, derives from a coating composition including theexpandable graphite. In one or more embodiments, the fabric backing maybe characterized by an expandable graphite concentration of at least 10g/m², in other embodiments at least 20 g/m², in other embodiments atleast 30 g/m², in other embodiments at least 40 g/m², in otherembodiments at least 50 g/m², in other embodiments at least 60 g/m², andin other embodiments at least 70 g/m². In these or other embodiments,the backing fabric may be characterized by an expandable graphiteconcentration of at most 150 g/m², in other embodiments at most 140g/m², in other embodiments at most 100 g/m², in other embodiments atmost 80 g/m².

Manufacture of Membrane Assembly

In one or more embodiments, where the membrane assembly includes afabric reinforcement laminated or sandwiched between layers of plasticmaterial, and the fabric reinforcement carries or has disposed thereonexpandable graphite, the manufacture of the membrane requires that theexpandable graphite be deposited on the fabric prior to manufacture ofthe membrane. On the other hand, where a membrane includes a fabricbacking that carries expandable graphite, the expandable graphite may bedeposited in the fabric prior to attachment of the fabric to themembrane or, in other embodiments, after the fabric is attached to themembrane.

The expandable graphite can be deposited on the fabric substrate (e.g.,substrate 30 or substrate 44) by using a variety of techniques. In afirst embodiment, the expandable graphite is formulated into a coatingcomposition by combining the expandable graphite with a binder. Thisbinder can be applied in the form of a wet coating to the fabric. Inother embodiments, the binder is applied to the fabric exclusive of theexpandable graphite, and following application of the binder to thefabric, and within sufficient time that the binder retains some level oftack or flowability to receive the expandable graphite, the expandablegraphite is deposited on the binder, which thereby serves to adhere theexpandable graphite to the fabric substrate.

Besides the foregoing, the membranes of the present invention can beprepared using conventional techniques. For example, methods forextruding thermoplastic sheet and laminating thermoplastic sheets to oneanother, optionally together with a reinforcing scrim, are known in theart. Likewise, methods for attaching a fabric backing, such as a fleecebacking, to a thermoplastic membrane are known in the art.

Installation of Membrane Assembly

In one or more embodiments, as suggested above, the membranes of thepresent invention can be secured to a roof deck using a variety oftechniques, all of which are known in the art. Accordingly, the skilledperson will be able to install the membranes of this invention to form aClass A roofing system without undue calculation or experimentation.

Various modifications and alterations that do not depart from the scopeand spirit of this invention will become apparent to those skilled inthe art. This invention is not to be duly limited to the illustrativeembodiments set forth herein.

1-20. (canceled)
 21. A roof assembly comprising: (a) a wood roof deck;and (b) a composite covering the wood roof deck, where the compositeincludes a thermoplastic membrane having first and second planarsurfaces and a fabric backing attached to at least a portion of thesecond planar surface of the membrane, where the fabric backing includesfirst and second planar surfaces, where the first planar surface of thefabric is attached to the membrane, where the second planar surface ofthe fabric has a coating composition disposed thereon, where the coatingcomposition includes expandable graphite dispersed within a binder,where the second planar surface of the fabric is proximate to said roofdeck relative to the second planar surface of the fabric, and whereinthe roof assembly achieves a Class A rating pursuant to UL 790 and/orASTM E
 108. 22. The roof assembly of claim 21, where the thermoplasticmembrane includes a thermoplastic polyolefin sheet.
 23. The roofassembly of claim 21, where the fabric includes a polyester fleece. 24.The roof assembly of claim 21, where the fleece is secured to thethermoplastic membrane by being at least partially embedded into theplanar surface of the thermoplastic membrane.
 25. The roof assembly ofclaim 21, where the composite is mechanically attached to the wood deck.26. The roof assembly of claim 21, where the composite is applieddirectly to the wood roof deck.
 27. The roof assembly of claim 21,further comprising a layer of insulation.
 28. The roof assembly of claim27, wherein the composite is applied directly over the layer ofinsulation which is applied directly over the wood roof deck.
 29. Theroof assembly of claim 21, where the composite includes a single fabricbacking.
 30. The roof assembly of claim 21, wherein the thermoplasticmembrane includes a first thermoplastic layer and a second thermoplasticlayer with a reinforcing scrim located between said first thermoplasticlayer and said second thermoplastic layer.
 31. A membrane compositecomprising: (a) a thermoplastic membrane having first and second planarsurfaces, where said thermoplastic membrane includes a firstthermoplastic layer and a second thermoplastic layer with a reinforcingscrim located between said first thermoplastic layer and said secondthermoplastic layer; and (b) a fabric secured to at least a portion ofthe second planar surface of the membrane, where the fabric includesfirst and second surfaces, where the first planar surface of the fabricis attached to the second planar surface of the membrane, where thesecond planar surface of the fabric has a coating composition disposedthereon, where the coating composition includes expandable graphitedispersed within a binder.
 32. The membrane composite of claim 31, wherethe fabric is in the form of a backing attached to the membrane.
 33. Themembrane composite of claim 31, where the fabric is a fleece.
 34. Themembrane composite of claim 31, where the fabric is a glass mat.
 35. Themembrane composite of claim 31, where said first and secondthermoplastic layers have a thickness from about 15 to about 70 mils.36. The membrane composite of claim 31, where the fabric is secured tothe thermoplastic membrane by being at least partially embedded into thesecond planar surface of the thermoplastic membrane.
 37. The membranecomposite of claim 31, where a lap edge of said second planar surface ofsaid thermoplastic membrane having the fabric secured thereto remainsexposed to thereby provide a weldable surface without said fabric.